Cold-rolled strip preservation consumes F20-1 Lamella Antirust Oil mainly at the exit of electrolytic galvanizing or temper-rolling lines. On lines running at 80–150 m/min, a three-roll or four-roll coater transfers the oil to the strip surface immediately before the recoiler. The application roll nip and oil bath temperature are held at 35–45 °C to stabilise kinematic viscosity during solvent evaporation. Target dry film mass is 0.8–1.5 g/m² per side, measured by infrared absorption or solvent extraction. The central process conflict is flash-off completion: residual solvent above 0.2 wt% at the recoiler causes adjacent laps to block and produce coil distortion, while film mass below 0.7 g/m² permits stack staining within 72 h at 40 °C and 70 % RH in humidity cabinet testing per ASTM D1748 or condensation testing per ISO 6270-2:2018. Exhaust velocity across the passline is set between 2.5 m/s and 5.0 m/s to remove solvent without disturbing the wet film. The preserved coil is later slit into blanks for appliance panels, automotive outer skins, and metal furniture. At the press shop, the film must be removable by alkaline immersion cleaning at 55–70 °C with 2–5 wt% silicate-free cleaner, leaving no staining on light-gauge zinc-coated substrate. Differential film weight between top and bottom surfaces creates uneven stacking and can shift slit-edge alignment by 0.2–0.8 mm in downstream stamping. The lamella structure of the dry film reduces edge wicking but does not substitute for sheared-edge protection; sheared edges may require supplementary dressing within 4 h if atmospheric corrosivity is category C3 per ISO 12944-2. Product-specific published data for F20-1 is limited, so operational values follow the solvent-deposited lamella category under ISO 6743-8 and mill-side calibration.

What Happens to Blanked Mild Steel If the Rust-Preventive Film Is Not Fully Dry Before Stacking?

When blanked mild steel parts leave mechanical presses and pass through a wash line, the subsequent application of F20-1 must be timed with a forced-drying tunnel to avoid stack-contact corrosion. Blanks are washed with an aqueous mild-alkaline cleaner at 50–60 °C and dried with compressed air before the oil is applied by flood-and-drain channel or reciprocating spray bar at 20–30 °C. Wet film thickness is set between 4–8 μm to achieve a dry film of 1.0–2.5 μm after solvent flash-off. The forced-drying tunnel must maintain 50–70 °C for 180–300 s; shorter residence times leave wet contact patches at stack interfaces. Stacking wet blanks produces black corrosion tracks along blank-to-blank contact points within 24–48 h, often visible after alkaline degreasing as grey-brown shadowing. The failure is not purely corrosion: residual solvent can soften forming-lubricant residues and create cling zones that cause double-blank feed failures on downstream servo presses. Drying above 75 °C accelerates solvent loss until film flow on vertical walls becomes discontinuous, leaving 0.3–0.5 μm dry spots at corner radii. Salt spray testing per ISO 9227:2022 for 24 h with a neutral 5 % NaCl solution typically produces rust grade no worse than ASTM D610 grade 9 on flat surfaces, while sheared edges show lower grades and must be protected separately. Blank stacks are stored under roof for 14–30 days before automotive panel stamping. Terminal parts include hood hinges, seat rails, door check straps, and battery carriers. If the film is removed by a phosphate line, oil carryover into the alkaline degreasing stage must remain below 50 mg/L in the bath to avoid phosphate sludge precipitation, controlled by pH 10.5–11.5 and overflow skimming.

Bearing assembly cells that reject VCI paper because of amine transfer into lithium complex greases apply F20-1 to cage-and-roller assemblies after demagnetisation and ultrasonic cleaning. The oil is supplied through a low-pressure flood trough at 25–35 °C, followed by a drainage period of 180–300 s on an inclined wire-mesh conveyor. Dry film mass is held at 0.5–1.0 g/m² to maintain a low-tack outer boundary without altering running clearance. This is critical for deep-groove ball bearings of size series 6200–6210, where film mass above 1.2 g/m² can be detected as an increase in post-greasing start-up torque on torque meters with 0.01 N·m resolution. Preserved components are not washed before grease packing; the oil must therefore show compatibility with polyurea and lithium thickener systems. Rust protection is screened under ASTM D665-19 in distilled water at 60 °C for 24 h, while ASTM D1748 humidity cabinet testing validates 120 h at 49 ± 1 °C. Bath maintenance is based on acid number ≤ 0.5 mg KOH/g and moisture content ≤ 0.05 wt%; water ingress from upstream cleaning chambers reduces film integrity because F20-1 is not specified for heavily wet surfaces. Basket loading must not exceed 80 % of working volume to allow uniform drainage from inner raceways. Terminals include electric motor bearings, fan hub cartridge bearings, and two-piece tapered roller bearing cups.

Fastener Packaging Under Tropical Moisture Load and K-Factor Drift Constraints

Packed in corrugated cartons with polyolefin liners for tropical destinations, fastener lots require a thin, non-tacky film that does not alter clamp-load relationships. After zinc plating and hydrogen embrittlement relief baking, or after phosphating, fasteners are charged into a dip-spin centrifuge. The basket is immersed in F20-1 at 20–30 °C, then spun at 250–350 rpm for 60–90 s to remove excess oil. This spin regime leaves a residual film of 0.8–1.5 g/m² on M6–M12 thread surfaces. Higher spin speeds remove film from thread roots, leaving unprotected microzones; lower speeds leave oil accumulation in hex recesses that migrates and stains carton liners. The critical fastener-specific parameter is K-factor drift. For zinc-plated M10 hexagon flange bolts, film mass above 2.0 g/m² can lower the coefficient of friction enough to increase clamp load at fixed torque by an estimated 3–6 %; film-free phosphated or zinc surfaces show wider scatter depending on plating thickness. Assembly plants using torque-angle monitoring may request reduced film weights on thread flanks but acceptable protection on the head and flange. Batch validation follows ISO 9227:2022 for 48 h neutral salt spray with acceptance at ≤ 5 % red rust area, evaluated by ASTM D610 grade 6. For fasteners entering electrical enclosures, the oil is screened against contamination assumptions in IEC 60664-1 and heavy-metal limits in Annex II of RoHS Directive 2011/65/EU, as well as EU REACH candidate list restrictions for final article residues. Terminal applications include battery cable bolts, door latch screws, engine bracket fasteners, and control cabinet hardware.

After hydrostatic testing and final drying, API line pipe and API coupling stock receive F20-1 by two methods: internally through a spray lance moving at 2–4 m/min and externally by a ring-type spray header at the run-out conveyor. Internal film mass is maintained at 2–5 g/m² for inside diameters of 60–219 mm; for pipe with inside diameter below 25 mm, the oil is diluted with 10–20 wt% aliphatic solvent with flash point above 40 °C to reduce plugging and permit air purging at 0.5–1.5 bar. The main process failure is oil accumulation at the six o’clock position after drainage; pipe must be rotated 90° every 20–30 min during curing, otherwise a drip-free interior cannot be guaranteed. For hydraulic cylinder barrel stock, internal residue after oil removal must not exceed 0.1 mg/cm² because downstream honing is impaired by free oil. Users therefore run a two-stage drying sequence of 30 min at 40 °C and 60 min at 25 °C before final capping. External protection is validated by ASTM D1748 for 120 h or outdoor exposure under ISO 12944-2 category C2 for 6 months. Couplings are dipped in the same oil at 30–40 °C and drained on pierced racks to avoid liquid bridges across thread crests. Terminal products include OCTG coupling stock, hydraulic cylinder tubes, and precision DOM tubes for agricultural equipment.

When Machined Cast-Iron Housings Are Transported Through Open-Sea Containers

In open-sea container transport, repeated dew point crossings cause condensation on ferrous surfaces even when vents are closed. Machined cast-iron pump housings and gearbox casings are dipped in F20-1 after final dimensional inspection and machining fluid removal. Dipping time is 60–120 s at 25–35 °C; drainage is conducted over a slatted stainless steel bench for 15–30 min. Resulting dry film mass is 3–6 g/m² on machined faces and 1.5–3 g/m² on as-cast outer surfaces. This gradient is intended: machined surfaces with surface roughness Ra 0.8–1.6 μm have less mechanical anchorage and require higher film mass, whereas as-cast surfaces with Ra 6.3–12.5 μm retain oil in graphite pockets and need less external film. The lamella-type film is used instead of hard-film waxes when assembly plants restrict VOC exposure and require removal by neutral or alkaline aqueous cleaners at 50–60 °C. Container shipment validation is frequently performed with cyclic condensation per ISO 6270-2:2018 for 240 h or salt spray per ISO 9227:2022 for 72 h, followed by inspection under ISO 8501-1 with rust grade not below Ri 1 on machined functional faces. The oil is not recommended for housings that will be painted without a hot alkaline wash, because residual film above 0.5 g/m² can cause cratering in two-pack epoxy primers applied at 20–25 μm dry film thickness. Terminals include gearbox casings, hydraulic pump bodies, compressor housings, and valve bodies shipped to assembly plants on other continents.

Tool and die storage in non-climate-controlled warehouses imposes intermittent condensation and finger-contact corrosion. Injection mould cores and die-casting cavity inserts are sprayed or brushed with F20-1 after polishing to Ra 0.05–0.2 μm. Wet film thickness is 6–10 μm, producing a dry film of 2–4 μm. High-polish surfaces drain oil faster than EDM-textured recesses, so inserts are wrapped in neutral pH paper after 20–30 min flash-off. Validation uses ISO 6270-2:2018 condensation testing for 168 h with no rust on polished surfaces. The main operational limit is that the oil does not remove existing fingerprints; parts must be handled with cotton gloves before application. Stored tools are later cleaned with solvent or alkaline immersion before first trial shots. Terminal tools include mould inserts, die-casting cores, and gauge blocks.